JP3134230B2 - Temperature characteristic compensation circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

The present invention relates to a temperature characteristic compensating circuit, and more particularly to a technology effective when applied to an electronic impedance device. For example, the present invention relates to a design for optimizing a temperature characteristic of a filter circuit in a bipolar linear semiconductor integrated circuit. It relates to technology that is effective to use.

[0002]

2. Description of the Related Art A filter using an electronic impedance device disclosed in Japanese Patent Publication No. 61-7053 (FIG. 3).
1 shows an example of the conventional temperature characteristic compensation method. The filter circuit shown in the figure is applied to a filter circuit for a noise reduction circuit. Q1 to Q12 are bipolar transistors, R1 to R6 are resistors, C is a time constant capacitor, Vcc is a power supply potential, and Vref is A reference potential generated by dividing the power supply potential Vcc by 1/2, CS1 to CS3 are current source circuits for supplying constant currents I1 to I3, Vin is an input, and Vout1 and Vout2 are outputs. Each circuit element in FIG. 3 has the following functions. Q3 and Q4 are applied with an input signal Vin and a feedback signal Vout2, and operate as voltage / current conversion circuits for outputting an output current related to a voltage difference between the input signal Vin and a current conversion resistor R1.
5, Q6, Q7, Q8 are voltage / current conversion circuits Q3, Q4
A first current that outputs an output current related to the output current of
Operating as a current conversion circuit, C operates as a capacitor forming a feedback signal Vout2 applied to the voltage / current conversion circuit when the output current of the first current / current conversion circuit is applied, and C1, Q2, Q9, Q10, Q1
1 and Q12 operate as a second current / current converter that outputs an output current related to the output currents of the voltage / current converters Q3 and Q4, and R2 receives the output current of the second current / current converter. By operating as an output resistance, a low-pass component of the input signal Vin is output from the output Vout2 of the first current / current conversion circuit, and a high-pass component of the input signal Vin is output from the output Vout1 of the second current / current conversion circuit. , A filter circuit for the noise reduction circuit is configured.

In this circuit, transfer functions H1 (S) and H2 of outputs Vout1 and Vout2 with respect to an input Vin.
(S) can be represented by the following equations (1) to (4).

(Equation 1) Here, the compensation of the temperature characteristic is performed by the following equations (3) and (4).
Constant currents I1, I supplied by the respective current source circuits CS1 to CS3
2, I3 by offsetting the temperature characteristics.

When the temperature characteristics are applied to each constant, the following equations (5) and (6) are obtained.

(Equation 2) Here, in the above-described conventional circuit, the resistance R1 is set to be sufficiently larger than the emitter forward resistance re1 of the bipolar transistors Q3 and Q4. As a result, the temperature coefficient β could be substantially regarded as the temperature coefficient of the resistor R1. Therefore, if the same type of resistor is used for R1 and R2, β = δ can be satisfied. As a result, the conditions for temperature characteristic compensation can be simplified as in the following equations (7) and (8).

(Equation 3)

In response to this, each of the constant currents I1, I2, I3
Were set as in the following equations (9) and (10).

(Equation 4) As described above, in this type of conventional circuit, the temperature characteristics can be compensated relatively easily because the circuit constant such as the resistance is sufficiently larger than the forward emitter resistance of the bipolar transistor.

[0006]

However, it has been clarified by the present inventors that the above-described technology has the following problems. That is, in a circuit built in a semiconductor integrated circuit, it becomes necessary to set constants of passive elements such as resistors to be small in order to take measures against offset or the like. However, if the constants of these passive elements are set to be small, the temperature characteristics of the forward emitter resistance of the bipolar transistor, which could be approximately ignored until now, cannot be ignored, and the temperature coefficient β is the temperature characteristic of the resistance. And the resistance varies in a complex manner depending on the ratio between the resistance and the emitter resistance. As a result, in the related art in which the temperature characteristic compensation is performed on the assumption that the temperature coefficient β has the temperature coefficient of only the resistor R1, the temperature characteristic compensation cannot be performed accurately.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a temperature characteristic compensator which can easily and accurately perform temperature characteristic control even in a situation where the temperature characteristic of the forward emitter resistance of a bipolar transistor cannot be ignored. To
It is to provide the technology called. The above and other objects and features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

[0008]

SUMMARY OF THE INVENTION Among the inventions disclosed in the present application, the outline of a representative one will be briefly described.
It is as follows. In other words, the temperature characteristic of the forward emitter resistance of the bipolar transistor is selectively canceled by the temperature characteristic of the current flowing through the emitter resistance. More specifically, the input signal
A return signal is applied, and the difference voltage and the current conversion resistor (R
The voltage / current conversion circuit that outputs the output current related to 1)
(Q3, Q4, etc.) and the above-mentioned voltage / current conversion circuit
A first current / output for outputting an output current related to the output current;
Current conversion circuit (Q5, Q6, etc.) and the first current
When the output current of the conversion circuit is applied,
Forming the feedback signal applied to the voltage-current conversion circuit
A capacitor (C) and the output of the voltage / current conversion circuit.
A second current / current that outputs an output current related to the force current
A conversion circuit (Q9, Q10, etc.) and the second current
Output resistance (R2) to which the output current of the conversion circuit is applied
And the output of the first current / current conversion circuit
And outputs the low-pass component of the input signal.
Outputs the high-pass component of the input signal by the output of the current conversion circuit.
And the voltage / current conversion circuit is
The input signal and the feedback signal are applied to the base and the
The current conversion resistor (R1) is connected between the transmitters.
Differential pair bipolar transistors (Q3, Q4) and
Current source circuits (Q15, R15) connected to the
3, Q14, R4), and the first power supply
The current-to-current conversion circuit is a differential pair bus that forms the output current.
The bipolar transistors (Q5, Q6) and their emitters
One current source circuit (Q16, R9) connected to the
Is constituted by the second current-current conversion circuit,
Differential-pair bipolar transistors forming its output current
(Q9, Q10) and the person connected to the emitter.
And two current source circuits (Q17, R10).
And a temperature compensation circuit for the filter circuit, the upper
The current value of the pair of current source circuits of the voltage / current conversion circuit
And the one current source of the first current / current conversion circuit
Circuit current value and the second current / current conversion circuit
Reference output for determining the current value of the two current source circuits
The bases are commonly connected to generate a current (I0).
A pair of bipolar transistors (Q25, Q26);
One emitter of the pair of bipolar transistors and
The resistor (R20) connected between the other emitter and
And one of the pair of bipolar transistors.
The base and collector of the polar transistor (Q26)
The above temperature characteristics in the form of a bandgap circuit connected
A compensation circuit is configured, and the voltage / current conversion circuit and the
1 current / current conversion circuit and the second current / current conversion circuit.
Path of each differential pair of bipolar transistors
The temperature characteristics of the emitter resistance
The temperature of the reference output current of the temperature characteristic compensation circuit of the form
This is offset by the degree characteristic.

[0009]

According to the above-mentioned means, it is possible to make the forward emitter resistance of the bipolar transistor apparently the temperature characteristic of an arbitrary resistance. Thereby, even in a situation where the temperature characteristics of the forward emitter resistance of the bipolar transistor cannot be ignored, the temperature characteristics can be compensated so that the temperature characteristics can be easily and accurately controlled. Achieved.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. In the drawings, the same reference numerals include the same or corresponding parts. FIG. 1 shows an embodiment of a main part of a temperature characteristic compensation circuit according to the present invention.

The circuit shown in FIG. 1 is a filter circuit for the noise reduction circuit shown in FIG.
1, a circuit for outputting a current serving as a reference for I2 and I3, wherein Q18 to Q38 are bipolar transistors.
Transistors, R11-R13, R20-R22, R2
7 is a resistor, Io1 and Io2 are reference output currents, and Vcc is a power supply potential. Io is a reference current of the bandgap circuit. In FIG. 1, the temperature characteristic of the potential VA at the point A is expressed by the following equation (11) based on T = 300 ° K (Ta = 27 ° C.).

(Equation 5)

Here, when a resistor of the same kind as the resistor R1 of the circuit shown in FIG. 3 is used for the emitter load resistor R22 of the transistor Q27, the temperature characteristic of the reference output current Io1 is as follows.
The following equation (12) is obtained.

(Equation 6) The forward emitter resistance re of the bipolar transistor when the reference output current Io1 is used as a current source
Has a temperature characteristic of only the resistor R22 as in the following equation (13).

(Equation 7)

Therefore, the current I of the filter circuit of FIG.
1 is given the temperature characteristic of the reference output current Io1,
That is, the reference output current Io1 is used as a reference for the current I1 in FIG.
When the resistor R22 has the same temperature characteristic as that of R1, the temperature coefficient β (Equation 2 and Eq. 3) in the circuit of FIG. 3 can be obtained only by R1 regardless of the ratio between the resistor R1 and re1. The temperature coefficient can be dependent. As described above, the temperature characteristics of an arbitrary resistance can be obtained from the apparent forward emitter resistance of the bipolar transistor.

Thus, even in a situation where the temperature characteristics of the forward emitter resistance of the bipolar transistor cannot be ignored, the temperature characteristics can be compensated so that the temperature characteristics can be controlled simply and accurately. FIG.
Shows an example in which the temperature characteristic compensation circuit of FIG. 1 is incorporated in a filter circuit for a noise reduction circuit.
The reference output currents Io1 and Io2 correspond to the bipolar transistors Q28 to Q37 and the resistors R14 to R19, R
23 to R26, etc., the current I1 to I1 in the filter circuit
It is designed to be transferred to I3.

In FIG. 1, Vou with respect to input Vin
The transfer characteristics of t1 and Vout2 are given by the following equation (1).
Same as (4). The following shows that the temperature coefficients α to ε of the respective terms in the equations (5) and (6) shown in Expression 2 can be obtained and the temperature characteristics can be compensated. First, the reference output current Io1 flowing through the collector of Q27 is supplied to a current source circuit CS1 comprising Q15 and Q14 by a current mirror.
a, CS1b are transferred to the constant currents I1, I1. As a result, I1 has the temperature characteristic of Io1. Here, R22
Is the same kind of resistance as R1 and has a temperature coefficient of χ, the temperature characteristic of I1 is given by the following equation (14) based on equation (12) of equation 6 when T = 300 ° K. become that way.

(Equation 8)

On the other hand, the temperature characteristic of 2re1 is obtained by flowing I1 having the same temperature characteristic as Io1 to Q3 and Q4.
According to Equation (12) of Equation 6, the temperature characteristic is the same as that of R22. In this case, since R22 and R1 are resistors of the same kind and their temperature characteristics are χ, R1 + 2re1 is given by the equation (15).
Becomes

(Equation 9) Thus, no matter what value R1 and re1 take, the temperature characteristic of R1 + 2re1 always has a temperature coefficient of only R1.

Next, the temperature characteristic of I2 is determined. I2 is
The reference output current Io2 flowing through the collector of Q38 is the current transferred by the current mirror, and Io2
It has the same temperature characteristics as. In this case, the emitter load resistor R27 of Q38 is an external resistor of the semiconductor integrated circuit, so that a resistor having an arbitrary temperature characteristic can be selected. The potential V at the point of the external terminal P1 of R27.
The temperature characteristic of P1 is equal to T as in the case of equation (11) of equation (5).
= 300 ° K, it is 1/300. Where R
Assuming that the temperature coefficient of 27 is ζ, the temperature characteristic of Io2 is expressed by the following equation (16).

(Equation 10)

Thus, the temperature characteristic of I2 is given by the following equation (1)
It becomes like 7).

[Equation 11] Next, as to the temperature characteristic of I3, since Io1 is transferred by the current mirror similarly to I1, Io1 is also obtained.
It has the same temperature characteristics as. Therefore, the temperature characteristic of I3 is as shown in the following equation (18).

(Equation 12)

As described above, the temperature characteristics of I1, I2 and I3 are given. Here, Equations (5) and (6) of Equation 2 are used.
In the above, if the same type as R1 and R27 is used for the resistor R2, the conditional expression (7) for temperature characteristic compensation shown in Expression 3 is obtained.
By applying to (8), the following equations (19) to (24) can be obtained.

(Equation 13) As a result, in the characteristics of the filter circuit, for the item A indicating the circuit gain, the temperature characteristics can be canceled (canceled) as in Expression (24) of Expression 13.

Further, the cutoff frequency ω of the filter circuit
Regarding o, the temperature coefficient 残 る remains according to the equation (23) of Expression 13, but this is due to the external resistor R27. Therefore, if R27 having no temperature coefficient is used, ω
The temperature characteristic of o can also be offset. Generally, the temperature characteristics of an external resistor can be significantly reduced as compared with a diffused layer resistor formed inside a semiconductor integrated circuit. As described above, according to the present invention, it is possible to replace the temperature characteristics of the forward emitter resistance re generated in the transistor with the temperature characteristics of the resistors that can be easily controlled accurately. Although this forward emitter resistance also occurs in the forward direction of the diode, it can be similarly replaced with a temperature characteristic of a resistor whose temperature characteristic can be easily compensated.

Thus, even when the temperature characteristics of the circuit are complicatedly generated by both the resistor and the transistor or the resistor and the diode, the temperature characteristics can be easily and accurately compensated. As described above, the invention made by the inventor has been specifically described based on the embodiments. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the invention. Not even.

For example, the temperature characteristic compensation may be such that a part of the active element is replaced with an element other than the bipolar transistor. In the above description, mainly the case where the invention made by the present inventor is applied to an active filter circuit for a noise reduction circuit, which is a field of use as a background, has been described. It can also be applied to temperature characteristic compensation of an oscillation circuit requiring high stability.

[0023]

The following is a brief description of an outline of typical inventions among the inventions disclosed in the present application. That is, the effect that the temperature characteristics can be easily and accurately controlled even under the condition where the temperature characteristics of the forward emitter resistance of the bipolar transistor cannot be ignored.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a main part of a temperature characteristic compensation circuit according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration example of a filter circuit to which a temperature characteristic compensation circuit according to the present invention is applied;

FIG. 3 is a diagram showing a configuration example of a conventional temperature characteristic compensation circuit together with an application example thereof.

[Explanation of symbols]

CS1 to CS3 Current source circuits I1 to I3 Constant currents with temperature characteristics compensated Io1, Io2 Reference output currents to compensate for temperature characteristics of forward emitter resistance Q1 to Q38 Bipolar transistors R1 to R27 Resistance Io Band gap circuit reference current

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Satoshi Sekiguchi 5-22-1, Kamimizuhoncho, Kodaira-shi, Tokyo Inside Hitachi Microcomputer System Co., Ltd. (72) Inventor Nobuaki Yoneya 5-22 Kamimizuhoncho, Kodaira-shi, Tokyo No. 1 in Hitachi Microcomputer System Co., Ltd. (72) Inventor Yuichi Okubo 111, Nishiyokote-cho, Takasaki City, Gunma Prefecture Inside Hitachi, Ltd. Takasaki Plant (56) References Japanese Patent Publication No. Sho 61-7053 (JP, B2) ( 58) Surveyed field (Int.Cl. ⁷ , DB name) H03H 11/54 H03H 11/04

Claims (1)

(57) [Claims] An input signal and a feedback signal are applied to output an output current related to a voltage difference between the input signal and a current conversion resistor.
A voltage-current conversion circuit , a first current-current conversion circuit that outputs an output current related to the output current of the voltage-current conversion circuit, and the output current of the first current-current conversion circuit is applied. A capacitor forming the feedback signal applied to the voltage-current conversion circuit, and a second current-current conversion circuit outputting an output current related to the output current of the voltage-current conversion circuit. An output resistor to which the output current of the second current / current conversion circuit is applied, and outputs a low-pass component of an input signal by an output of the first current / current conversion circuit; The high-pass component of the input signal is output by the output of the current-current conversion circuit. The voltage-current conversion circuit is configured such that the input signal and the feedback signal are applied to the base and the high-pass component is applied between the emitter. A differential pair bipolar transistor to which the current conversion resistor is connected, and a pair of current source circuits connected to the emitter thereof, wherein the first current / current conversion circuit forms the output current. The second current-current conversion circuit is constituted by a differential pair bipolar transistor and one current source circuit connected to the emitter thereof, wherein the second current-current conversion circuit forms the output current, A temperature characteristic compensation circuit for a filter circuit constituted by one current source circuit connected to an emitter, wherein a current value of said pair of current source circuits of said voltage / current conversion circuit and said first current A basis for determining a current value of the one current source circuit of the current conversion circuit and a current value of the one current source circuit of the second current / current conversion circuit A pair of bipolar transistors having bases connected together to generate an output current, and a resistor connected between one emitter and the other emitter of the pair of bipolar transistors; The temperature characteristic compensating circuit is configured in the form of a bandgap circuit in which a base and a collector of one of the bipolar transistors are connected, and the voltage / current converting circuit, the first current / current converting circuit, and the second Offsetting the temperature characteristics of the forward emitter resistance of each differential pair bipolar transistor of the current-to-current conversion circuit of claim 2 with the temperature characteristics of the reference output current of the temperature characteristic compensation circuit in the form of the band gap circuit. A temperature characteristic compensation circuit characterized by the following.